It only becomes the insurance companies problem if he insured it for the full amount that he paid for the car. Otherwise it is only their responsibility to pay out the insured value of the car. Beyond that it is time to take it out of the hide of the person that hit him. I was hit by and uninsured driver and in a hit and run. Both times the damage was repaired by shredding the person that hit me apart using the insurance company and the courts, even had the hit and run guy tossed in jail that was fun.
It is much better to work with the insurance companies and destroy the idiot that hit than it is forget about that person and try and go after your insurance company because they have deeper pockets. They also tend to have better lawyers and don't mind footing the bill to go after someone else.
